Never did a servant understand his Boss so well, nor get the better of him in so many ways... 
Rochester..aka, Eddie Anderson
Eddie Anderson
As the infuriating but highly likable 'Rochester' - Jack Benny's wise-cracking, domestic employee and foil - actor and comedian Eddie Anderson was a consummate performer and, at his peak,  one of the highest paid African-American entertainers in the industry. Anderson's squawky high-pitched voice and  riotous one-liners made him a favourite with audiences. It's hard to imagine Benny without him and to his credit, Benny knew what he had, as it was an association that was to span many years. "Rochester' joined Jack on radio, TV and film,  continuing with the Jack Benny troupe into the 1970s.
Anderson's distinctive voice was reputedly the result of  an early stint as a a newspaper spruiker in San Francisco, where he damaged his vocal chords attempting to be the loudest seller on the street. He made his first appearance in The Jack Benny Program in 1937 with a bit part as a porter - over the next few years, a few more small parts followed.  Audience reaction proved to be so positive toward the gravel-voiced bit player, that a permanent role was created for him. It proved to be a wise decision, as Anderson became an indispensable cast member and a tremendous asset to the Benny shows.

Anderson was born in Oakland in 1905, the son of a minstrel father and tight-rope walking mother and had worked in Vaudeville as an accomplished dancer. His first film was in The Green Pastures (1936) and in 1938, in between radio assignments, he made  Kentucky, You Can't Take it With You and Jezebel. Although the role of Rochester become the focus of Anderson's career, he did go on to make a few more films, including Brewster's Millions(1945), The Show-off (1948) and It's a Mad, Mad World (1963).

Repartee and Racism
Playing Jack Benny's valet/butler afforded Anderson a great opportunity for some great lines and situations and via Rochester, audiences got a greater 'insight' into Benny's onscreen character, which was essentially a  caricature of the real life man - vain, miserly and prone to excessive bragging. As  valet and employer, the pair developed an intimate relationship and often had running gags between them, one of which included hairpieces, with Rochester joking that Benny "had hair at home he hasn't used yet" (in real life Benny had his own hair). Benny in turn, often launched amusing jibes at Rochester's bad habits - gambling, women, drinking and work avoidance. There was however, an underlying warmth and fondness to the repartee that provided much of the spark which made the act so enduring and memorable.

The comedy of the whole Jack Benny apparatus succeeded in no small part because it was character-driven rather than gag-driven and as audiences were to discover week after week...Rochester was a terrifically funny character.While the role of Rochester was indicative of the African American typecasting of the period, Rochester's character developed into something much more than just a stereotypical master/servant relationship. For one thing the canny Rochester was often able to outwit his boss and for another, the dynamic between the two characters was so relaxed, easy and amusing, it's difficult to think of Rochester as exploited in any way. Nonetheless,  the Jack Benny shows were products of their era and in real life racial issues and discriminations did rear their ugly head.

During the second world war, Rochester could not tour with the show because the discriminatory standards of the day would have demanded separate living quarters for a black entertainer. Benny was defensive of his co-star and intolerant of the kind of hypocritical, illogical prejudice that defined attitudes among some of his fellow countrymen. In his unpublished memoirs, Benny describes an experience he had during that WWII tour.  While sitting in a canteen in Abadan, he was confronted by a US sergeant who was bemoaning Anderson's absence from the show and eulogising Rochester, albeit in racist language:
 'You really love Rochester, don't you?' I said.
'Love him? Why, sir, ah tell you ah'd walk ten miles to see that Rochester.'
'You love him so much, huh? Well, let me ask you something. Would you walk into this canteen and sit down with him at the same table?'
His expression got nasty. 'Well, sir, ah come from a part of the country where we don't sit down with nigras.'
'I thought so, young man, and that's why I didn't bring Rochester on this trip. I didn't want him to be embarrassed and humiliated by ignorant folks like you. You say you love Rochester. You'll walk ten miles to see him perform. But you won't sit down at the same table and drink a coke with him. You make me sick.'
I walked out of the canteen.